The present invention relates to a drying section of a paper machine having several drying groups wherein the quantity of drying cylinders may be reduced, particularly by including an additional press means in the drying section for drying the web.
A drying group within a drying section passes the web to be dried sequentially over a series of drying cylinders. Within a drying section, the drying groups may be either double tier, directly heating the opposite sides of the web at successive drying cylinders, or single tier, directly heating the same side of the web at successive drying cylinders.
U.S. Pat. No. 4,934,067 discloses a single tier drying section in which the web is transferred between successive single tier drying groups by bringing the dryer wires or felts of two successive drying groups together in the region of the group to group transfer and thereby bringing both wires into contact with the opposite sides of the web which lies between them. In this connection, the drier wires of the two successive single tier drying groups are conducted over suction rolls which are positioned after the last drying cylinder in the upstream group or before the first drying cylinder in the downstream group. Such devices counteract fluttering and tearing of the web in the region of transfer by avoiding a free, unsupported path or open draw of the web of paper.
To improve or increase the drying capacity, an increased number of drying cylinders are employed, possibly divided into even more drying groups, which represents a considerable expense.